Aerojet Propulsion Assists Voyager 1 Precision Maneuver at the Edge of the Solar System

SACRAMENTO, Calif. – Aerojet, a GenCorp (NYSE: GY) company, announced today that its thrusters on the Voyager 1 spacecraft assisted in several critical repositionings of the spacecraft over 10 billion miles away from the sun, at the edge of the solar system.

On March 8, 2011, the 34-year-old Voyager 1 spacecraft did the deep space equivalent of a gymnastics routine at the Olympics as it rolled 70 degrees counterclockwise from its normal orientation and held the position by spinning gyroscopes for two hours and 33 minutes. Until a recent preparatory test, the last time either of the two Voyager spacecraft rolled and stopped in a gyro-controlled orientation was on Feb. 14, 1990.

Voyager 2 was launched on Aug. 20, 1977. The launch of Voyager 1 followed on Sept. 5, 1977. Since their launch, both spacecraft have traveled outward from Earth, providing decades of discoveries about our solar system. This past March 7, Voyager 1 was located about 17 billion kilometers (11 billion miles) away from the sun and Voyager 2 was 14 billion kilometers (nine billion miles) away on a different trajectory. Each of the spacecraft carries an attitude control system including 16 Aerojet monopropellant thrusters. The thrusters are used in concert with Voyager’s gyroscopes to maneuver the spacecraft.

In June 2010, the spacecraft’s instruments indicated that the solar wind was slowly dropping to zero. This meant that Voyager was reaching the edge of our solar system. The Voyager science team conducted the precision roll maneuvers to determine the strength and direction of the solar wind at the edge of the solar system, in a continuing effort to understand the shape of our solar system’s solar wind “bubble.” This will allow the Voyager science team to estimate how much farther it is to the end of our solar system and when Voyager will become the first spacecraft from Earth to enter interstellar space.

In preparation for the precision roll maneuvers, Voyager engineers performed a series of test maneuvers prior to the main repositioning event, similar to an athlete training for a major competition. On Feb. 2 the Voyager team maneuvered the spacecraft for two hours and 15 minutes. When the test data from Voyager 1 was received on Earth some 16 hours later, the mission team verified that the test was successful and that the spacecraft had no problem in reorienting itself and locking back onto its guide star, Alpha Centauri. The instrument science team confirmed that the maneuvers allowed the spacecraft to acquire the kind of information about the solar wind that it needed, and mission planners gave Voyager 1 the go-ahead for more rolls and longer holds. There were additional maneuvers, with the longest hold lasting three hours and 50 minutes. The Voyager team now plans to execute a series of weekly rolls for this purpose every three months.

“Aerojet is astonished at the longevity of the Voyager spacecraft including our thrusters,” said Aerojet Director, Joe Cassady. “The science returned by these spacecraft has transformed humankind’s understanding of our solar system. Aerojet is very proud to be a part of the Voyager missions and their latest discoveries at the edge of our solar system and the start of interstellar space.”